There has conventionally been proposed a system which uses a designated image file format to transmit, to a designated destination, an image read from a document by an image input apparatus such as a scanner or an image received by the reception unit of the system.
An example of the system is a multi-functional peripheral having transmission and reception units. In the multi-functional peripheral, when an image read by a scanner is to be transmitted, the image is converted into a proper image file format designated by the user. Examples of the file format are TIFF, JFIF, and PDF. In terms of security, an image is sometimes encrypted and transmitted in accordance with a user instruction. For example, an image is transmitted using a PDF encryption function (e.g., Japanese Patent Laid-Open No. 2002-271553).
Most multi-functional peripherals also have a function of storing, in, e.g., an internal storage apparatus, an image which has failed in transmission or a transmitted image in accordance with a cancel instruction by the user, and transmitting the image to another destination in accordance with a user instruction. With this function, an image which has failed in transmission owing to disconnection from the network, a server problem, or the like can be transmitted to another destination without reading the image again.
According to the prior art, however, a change of the transmission destination of an image stored in the internal storage apparatus of the multi-functional peripheral is based on a transmission instruction designated by the user, and change operation is not limited. Operation of changing the transmission destination can be performed by any user who uses the multi-functional peripheral.
By destination change operation by another user, an image may be transmitted to a destination not intended by a user who has input a transmission job. In this case, a transmission job which has undergone encryption processing in transmission cannot be decrypted even if it is transmitted to an unintended destination. However, a transmission job which does not undergo any encryption processing may allow a third party to see its transmission contents. This impairs the security of an image.